Pattern Recognition
Digital Realisation of Self-Organising Maps
Allinson, Nigel M., Johnson, Martin J., Moon, Kevin J.
Background The overall aim of our work is to develop fast and flexible systems for image recognition, usually for commercial inspection tasks. There is an urgent need for automatic learning systems in such applications, since at present most systems employ heuristic classification techniques. This approach requires an extensive development effort for each new application, which exaggerates implementation costs; and for many tasks, there are no clearly defined features which can be employed for classification. Enquiring of a human expert will often only produce "good" and "bad" examples of each class and not the underlying strategies which he may employ. Our approach is to model in a quite abstract way the perceptual networks found in the mammalian brain for vision. A back-propagation network could be employed to generalise about the input pattern space, and it would find some useful representations. However, there are many difficulties with this approach, since the network structure assumes nothing about the input space and it can be difficult to bound complicated feature clusters using hyperplanes. The mammalian brain is a layered structure, and so another model may be proposed which involves the application of many two-dimensional feature maps. Each map takes information from the output of the preceding one and performs some type of clustering analysis in order to reduce the dimensionality of the input information.
Neural Network Star Pattern Recognition for Spacecraft Attitude Determination and Control
Alvelda, Phillip, Martin, A. Miguel San
ABSTRACT Currently, the most complex spacecraft attitude determination and control tasks are ultimately governed by ground-based systems and personnel. Conventional on-board systems face severe computational bottlenecks introduced by serial microprocessors operating on inherently parallel problems. New computer architectures based on the anatomy of the human brain seem to promise high speed and fault-tolerant solutions to the limitations of serial processing. INTRODUCTION By design, a conventional on-board microprocessor can perform only one comparison or calculation at a time. Image or pattern recognition problems involving large template sets and high resolution can require an astronomical number of comparisons to a given database.
Digital Realisation of Self-Organising Maps
Allinson, Nigel M., Johnson, Martin J., Moon, Kevin J.
Background The overall aim of our work is to develop fast and flexible systems for image recognition, usually for commercial inspection tasks. There is an urgent need for automatic learning systems in such applications, since at present most systems employ heuristic classification techniques. This approach requires an extensive development effort for each new application, which exaggerates implementation costs; and for many tasks, there are no clearly defined features which can be employed for classification. Enquiring of a human expert will often only produce "good" and "bad" examples of each class and not the underlying strategies which he may employ. Our approach is to model in a quite abstract way the perceptual networks found in the mammalian brain for vision. A back-propagation network could be employed to generalise about the input pattern space, and it would find some useful representations. However, there are many difficulties with this approach, since the network structure assumes nothing about the input space and it can be difficult to bound complicated feature clusters using hyperplanes. The mammalian brain is a layered structure, and so another model may be proposed which involves the application of many two-dimensional feature maps. Each map takes information from the output of the preceding one and performs some type of clustering analysis in order to reduce the dimensionality of the input information.
A Bifurcation Theory Approach to the Programming of Periodic Attractors in Network Models of Olfactory Cortex
Bill Baird Department of Biophysics U.C. Berkeley ABSTRACT A new learning algorithm for the storage of static and periodic attractors in biologically inspired recurrent analog neural networks is introduced. For a network of n nodes, n static or n/2 periodic attractors may be stored. The algorithm allows programming of the network vector field independent of the patterns to be stored. Stability of patterns, basin geometry, and rates of convergence may be controlled. Standing or traveling wave cycles may be stored to mimic the kind of oscillating spatial patterns that appear in the neural activity of the olfactory bulb and prepyriform cortex during inspiration and suffice, in the bulb, to predict the pattern recognition behavior of rabbits in classical conditioning experiments.
Neural Network Star Pattern Recognition for Spacecraft Attitude Determination and Control
Alvelda, Phillip, Martin, A. Miguel San
ABSTRACT Currently, the most complex spacecraft attitude determination and control tasks are ultimately governed by ground-based systems and personnel. Conventional on-board systems face severe computational bottlenecks introduced by serial microprocessors operating on inherently parallel problems. New computer architectures based on the anatomy of the human brain seem to promise high speed and fault-tolerant solutions to the limitations of serial processing. INTRODUCTION By design, a conventional on-board microprocessor can perform only one comparison or calculation at a time. Image or pattern recognition problems involving large template sets and high resolution can require an astronomical number of comparisons to a given database.
A Bifurcation Theory Approach to the Programming of Periodic Attractors in Network Models of Olfactory Cortex
Bill Baird Department of Biophysics U.C. Berkeley ABSTRACT A new learning algorithm for the storage of static and periodic attractors in biologically inspired recurrent analog neural networks is introduced. For a network of n nodes, n static or n/2 periodic attractors may be stored. The algorithm allows programming of the network vector field independent ofthe patterns to be stored. Stability of patterns, basin geometry, and rates of convergence may be controlled. Standing or traveling wave cycles may be stored to mimic the kind of oscillating spatial patterns that appear in the neural activity of the olfactory bulb and prepyriform cortex during inspiration and suffice, in the bulb, to predict the pattern recognition behavior of rabbits in classical conditioning experiments.
Neural Network Star Pattern Recognition for Spacecraft Attitude Determination and Control
Alvelda, Phillip, Martin, A. Miguel San
Phillip Alvelda, A. Miguel San Martin The Jet Propulsion Laboratory, California Institute of Technology, Pasadena, Ca. 91109 ABSTRACT Currently, the most complex spacecraft attitude determination and control tasks are ultimately governed by ground-based systems and personnel. Conventional on-board systems face severe computational bottlenecks introduced by serial microprocessors operating on inherently parallel problems. New computer architectures based on the anatomy of the human brain seem to promise high speed and fault-tolerant solutions to the limitations of serial processing. INTRODUCTION By design, a conventional on-board microprocessor can perform only one comparison or calculation at a time. Image or pattern recognition problems involving large template sets and high resolution can require an astronomical number of comparisons to a given database.
Learnability and the Vapnik-Chervonenkis dimension
Blumer, A. | Ehrenfeucht, A. | Haussler, D. | Warmuth, M.
In this paper we extend Valiant's model to learning concepts defined by regions in Euclidean n-dimensional space E", n 2 1. The general techniques we develop lead to new results in Boolean domains as well. Our methods are based on the pioneering work of Vapnik and Chervonenkis [6 I-631 on the distribution-free convergence of empirical probability estimates and its application to the theory of pattern recognition. These methods provide a unified treatment of some of Valiant's results, and extend previous results of Pearl [50, 5 I] and Devroye and Wagner ([ 151, see also [ 141) along with our results from [lo]. In learning a class C of concepts (e.g., subsets of E") from examples, a single target concept is selected from C and we are given a finite sequence of points in E", each labeled " 1" if it is in the target concept (a positive example) and "0" if it is not (a negative example). This set is called a sample of the target concept. A learning function for C is a function that, given a large enough randoml:y drawn sample of any target concept in C, returns a region in E" (a hypothesis) that is with high probability a good approximation to the target concept. More precisely: (1) We let P be a fixed probability distribution on E" and assume that examples are created by drawing points independently at random according to P. (2) The error of a hypothesis is taken to be the probability that it disagrees with the target concept on a randomly drawn example, that is, the error is just the probability (according to P) of the symmetric difference between the hypothesis and the target concept.
A Computer Simulation of Olfactory Cortex with Functional Implications for Storage and Retrieval of Olfactory Information
Bower, James M., Wilson, Matthew A.
A Computer Simulation of Olfactory Cortex With Functional Implications for Storage and Retrieval of Olfactory Information Matthew A. Wilson and James M. Bower Computation and Neural Systems Program Division of Biology, California Institute of Technology, Pasadena, CA 91125 ABSTRACT Based on anatomical and physiological data, we have developed a computer simulation of piriform (olfactory) cortex which is capable of reproducing spatial and temporal patterns of actual cortical activity under a variety of conditions. Using a simple Hebb-type learning rule in conjunction with the cortical dynamics which emerge from the anatomical and physiological organization of the model, the simulations are capable of establishing cortical representations for different input patterns. The basis of these representations lies in the interaction of sparsely distributed, highly divergent/convergent interconnections between modeled neurons. We have shown that different representations can be stored with minimal interference. Further, we have demonstrated that the degree of overlap of cortical representations for different stimuli can also be modulated. Both features are presumably important in classifying olfactory stimuli.